460 " " CLEAR : INPUT "a=";A#,"b=";B#,"step=";C: DIM A#(C+1)
  461 E=1E-8,K#=B#-A#:X#=A#: GOSUB 1:D#=F#:X#=B#: GOSUB 1:Q#=F#
  462 A#(1)=(D#+Q#)/2:M=1: FOR J=1 TO C:P#=0:L#=K#/(2*M)
  463 FOR I=1 TO 2*M-1 STEP 2:X#=(A#+I*L#): GOSUB 1:Q#=F#:P#=P#+Q#
  464 NEXT I:A#(J+1)=(P#/M+A#(J))/2:N=1: FOR I=J TO 1 STEP -1
  465 N=N*4:A#(I)=A#(I+1)+(A#(I+1)-A#(I))/(N-1)
  466 NEXT I:M=M*2,G#=A#(1)*K#: IF J=1 THEN 468
  467 IF  ABS (G#-H#)<E* ABS G# PRINT "Integral=";G#: END 
  468 H#=G#: NEXT J: PRINT "too slow": END